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Spectroscopic analysis of high electric field enhanced ionization in laser filaments in air for corona guiding

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High Power Laser Science and Engineering 2016年第1期4卷 52-57页

作者： Yingxia Wei Yaoxiang Liu Tie-Jun Wang Na Chen Jingjing Ju Yonghong Liu Haiyi Sun Cheng Wang Jiansheng Liu Haihe Lu See Leang Chin Ruxin Li State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Centre d’Optique Photonique et Laser (COPL) and Dpartement de physiquede gnie physique et d’optiqueUniversit Laval

We report on a systematic experimental study on the fluorescence spectra produced from a femtosecond laser filament in air under a high electric field. The electric field alone was strong enough to create corona discharge(CD). Fluorescence spectra from neutral and ionic air molecules were measured and compared with pure high-voltage CD and pure laser filamentation(FIL). Among them, high electric field assisted laser FIL produced nitrogen fluorescence more efficiently than either pure CD or pure FIL processes. The nonlinear enhancement of fluorescence from the interaction of the laser filament and corona discharging electric field resulted in a more efficient ionization along the laser filament zone, which was confirmed by the spectroscopic measurement of both ionization-induced fluorescence and plasma-scattered 800 nm laser pulses. This is believed to be the key precursor process for filament-guided discharge.

关键词： femtosecond laser filamentation filament induced fluorescence spectroscopy laser guided discharges

Extending optical filaments with phase-nested laser beams

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Photonics Research 2018年第12期6卷 1130-1136页

作者： JIA-QI LU PING-PING LI DAN WANG CHENGHOU TU YONGNAN LI HUI-TIAN WANG School of Physics and Key Laboratory of Weak-Light Nonlinear Photonics Nankai UniversityTianjin 300071China National Laboratory of Solid State Microstructures and School of Physics Nanjing UniversityNanjing 210093China Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

Extending the length of femtosecond laser filamentation has always been desired for practical applications. Here,we demonstrate that significant extending of a single filament in BK7 glass can be achieved by constructing phasenested beams. The filamentation and the following energy replenishment are assembled in a single phase-nested beam. The central part of the phase-nested beam is an apertured Gaussian beam, which is focused into one focal spot to produce a short filament. In contrast, the rest of the annular part converges gradually towards the central axis to continuously replenish the energy for supporting the regeneration of filaments. The common-path generating system ensures the stability of generated filaments and easily optimizes the beam parameters to obtain the longest high-quality filament due to its flexibility. In addition, we discuss the significance of continuous replenishment for extending filaments and the potential for generating more extended filaments based on this method.

关键词： Femtosecond laser hole BK7 glass Short filament

Induction and cultivation of cloned filaments of Polysiphonia urceolata(Rhodomelaceae,Rhodophyta)

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Chinese Journal of Oceanology and Limnology 2011年第6期29卷 1260-1266页

作者：王金霞邵魁双程滨陆勤勤周百成 Institute of Oceanology Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences National Marine Environmental Monitoring Center Institute of Oceanology & Marine Fisheries

A filamentous clone ofPolysiphonia urceolata was regenerated from segments cut from the fronds of gametophytes. Unlike wild thalli with short virgate branchlets, the clone was filamentous with few branches. Many transparent trichoblasts arose from pericentral cells during the induction culture, but these were seldom observed during normal growth. The trichoblasts were uniseriate, often colorless, and formed lobed rhizoids rapidly when they came into contact with solid substrates. In addition to morphological characteristics, the photosynthetic properties and growth conditions of the clone differed from those of the mother plant. Cross-gradient light and temperature culture experiments revealed that the most favorable conditions for culture of the filamentous clone were 22℃ and 95-120 gE/（m2-s） light intensity. The photosynthetic light saturation value for filaments was approx. 100 gE/（m2.s）, which is far lower than that of wild thalli. These results could be used to develop techniques for mass cultures of P. urceolata in photobioreactors for production of seed stock or bioactive products.

关键词： Polysiphonia urceolata Rhodophyta filament culture

Intermediate filaments in Higher Plant Cells and Their Reconstitution in vitro

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Science China Chemistry 1993年第8期36卷 940-947页

作者：杨澄邢力翟中和 Department of Biology Peking University Beijing 100871 PRC

Delicate networks of 10-nm filaments were found to exist widely in suspension cells of cultured carrot and root tip cells of pea by selective extraction combined with whole mount and diethylene glycol distearate plastic embedment-free section for electron microscopy. These filament components are polypeptides of 52, 58, 62—64 and 50kD using Western blot analysis. A relatively uniform 10-nm filaments, as well as bundle of such filaments could be reconstituted in vitro. The reconstituted filaments were indistinguishable from native plant intermediate filaments in morphology and protein components. Thus the intermediate filaments are actually present in cytoplasm of higher plants. We also found no obvious specificity in tissues and species by comparison of the proteins among various types of plant cells.

关键词： intermediate filament selective fractionation embedment-free section Western blot keratin filament assembly.

Structure of neurofilaments studied with scanning tunneling microscopy

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Chinese Science Bulletin 1998年第21期43卷 1805-1809页

作者： Jie Liu Xiangjun Tong Shijin Pang Zhonghe Zhai Beijing Univ Coll Life Sci Beijing 100871 Peoples R China Chinese Acad Sci Inst Phys Ctr Condensed Matter Phys Beijing Lab Vacuum Phys Beijing 100080 Peoples R China

Neurofilaments (NFs) were isolated from bovine spinal cord. The structure of purified NFs was studied by scanning tunneling microscopy (STM). The STM images showed that NF was composed of a long core filament and numerous sidearms flanking the rod regularly. The diameter of the rod was about 10 nm (10.2±0.8 nm). Most of the sidearms were short and the distance between two adjacent sidearms was approximately 10 nm. There were some long sidearms between two proximal core filaments. The distance between two adjacent long sidearms was 21 nm. A three-quarter-staggered fashion of native NF structure was put forward.

关键词： neurofilament intermediate filament scanning tunneling microscopy.

THE INFLUENCE OF SPINNING CONDITION ON STRUCTURE & PROPERTIES OF MASS-DYED SUPERFINE PP AS-SPUN filamentS

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Journal of China Textile University(English Edition) 1996年第2期13卷 11-17页

作者：朱美芳陈彦模

The effect of colorant additive on the rheology of PP polymer melt and the influence of spinning conditions on the crystalline and orientation structure of mass-dyed as-spun PP filament are reported. The △E~~~ value for all colored chips is higher than that of blank chip to a varying degree. The crystallinity and orientation degree of dyed PP as-spun filament decrease with increasing melt temperature, decreasing spinning speed and increasing denier per filament (dpf), while the crystallinity of dyed as-spun filament increases with the content of colorant additive as a nucleation agent.

关键词： spinning condition dyed additive fine PP filament

Assembly characteristics of plant keratin intermediate filaments in vitro

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Science China(Life Sciences) 1999年第5期42卷 485-493页

作者：闵光伟杨澄佟向军翟中和

After selective extraction and purification, plant keratin intermediate filaments were reassembled in vitro. Scanning tunneling microscope (STM) and transmission electron microscope (TEM) micrographs showed that acidic keratins and basic keratins can assemble into dimers and further into 10 nm filaments in vitro. In higher magnification images , it can be seen that fully assembled plant keratin intermediate filaments consist of several thinner filaments of 3 nm in diameter, which indicates the formation of protofilaments in the assembly processes. One of the explicit features of plant keratin intermediate filaments is a 24-25 nm periodic structural repeat alone the axis of both the 10 nm filaments and protofilaments. The periodic repeat is one of the fundamental characteristic of all intermediate filaments, and demonstrates the half staggered arrangement of keratin molecules within the filaments.

关键词： intermediate filament keratin in vitro assembly scanning tunneling microscope (STM).

Optimization of Cross-sectional Shapes of the Bi-2223/Ag Wires before Flat Rolling

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Chinese Journal of Mechanical Engineering 2009年第6期22卷 890-895页

作者： LU Yongjin ZENG Pan LEI Liping SUN Jianfeng Department of Mechanical Engineering Tsinghua University Beijing 100084 China Key Laboratory for Advanced Materials Processing Technology of Ministry of Education Tsinghua University Beijing 100084 China Innova Superconductor Technology Co. Ltd. Beijing 100176 China

Rolling process plays an important role in the manufacture of Bi-based high temperature superconductor tapes, and the plastic flow regularities of the superconducting wires during deformation will directly affect the ultimate quality of the tapes. In order to investigate the effect of cross-sectional shapes before fiat rolling on the performance and homogeneity of the tapes, some numerical models of Bi-2223/Ag wires with different cross-sectional shapes including circular, square, elliptical and racetrack cross-sections are constructed during the rolling process. By comparing the relative density, logarithmic strain ratio and length-width ratio on the filaments, it is revealed that Bi-2223/Ag wire with special-shaped cross-section can achieve better conductivity than the round wire, in particular, the racetrack cross-sectional wire has the second best performance among four wires. Based on material processability and experimental condition, tri-pass racetrack drawing technique is employed to optimize the process and obtain racetrack cross-sectional wire. The rolling process of Bi-2223/Ag wire with racetrack cross-section causes more intensive deformation of filaments in the center of the tape and achieves the filaments with larger length-width ratio. Also, the deformation distribution of filaments verifies the numerical results. Consequently, the racetrack drawing technique can be utilized for a reference during the mechanical processing and to increase the current transmission capacities of Bi-2223/Ag tapes.

关键词： rolling cross-sectional shape filament modelling

MyD88 self-assembles into supramolecular filaments to amplify NF-κB signaling

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MyD88 self-assembles into supramolecular filaments to amplif...